gen_dispatch: Ignore 'glsc2' API

The new GL registry XML contains the 'glsc2' identifier for the OpenGL
SC 2.0 API. We can safely ignore it, since we don't really know what to
do with it, at the moment.

src/gen_dispatch.py

@@ -375,6 +375,8 @@ class Generator(object):
                 human_name = 'WGL {0}'.format(version)
                 condition = 'true'
                 loader = 'epoxy_gl_dlsym({0})'
+            elif api == 'glsc2':
+                continue
             else:
                 sys.exit('unknown API: "{0}"'.format(api))